On the Correct Roles of Induction and Deduction in Human Life: Two Sentences from Ayn Rand’s Theory of Concepts

Original thinkers often state their identifications succinctly.

Ayn Rand’s notion of measurement omission (Introduction to Objectivist Epistemology, chap. 2) in the formation of concepts is one such identification. Here is another (p. 28):

The process of observing the facts of reality and of integrating them into concepts is, in essence, a process of induction. The process of subsuming new instances under a known concept is, in essence, a process of deduction.

These brief and to the point sentences state not just the two fundamental methods of cognition, but more importantly, the correct roles of induction and deduction in human life.

And by “human life,” I mean science as well as everyday life.

Induction is the process of generalization, of forming universal concepts based on our observation of particular objects or events. The definition of a single concept states a principle—all humans possess the capacity to reason, for example—and the combination of several or many concepts and principles builds our knowledge of reality and, in some cases, establishes the physical, biological, and human sciences.

Induction is conceptualization. From an early age, probably before we can assign words to them, we all practice the inductive formation of universal concepts.

This was my example in an earlier post of our daughter, before she could walk or talk, laughing heartily at her first sight of a bouncing ball (Applying Principles, pp. 322-24). She identified a universal, because her mind, to quote Aristotle (Posterior Analytics, 100a13), “is so constituted as to be capable of this process” (though the universal is not “in the thing,” as Aristotle assumed).

Rand’s identification describes in general terms the true nature of induction and makes the biological and human sciences as exact and valid as the physical sciences.*

Deduction is the process of identifying particular objects or events as instances of the general knowledge we have already acquired. The process, more accurately, is one of application.

Deduction is what Sherlock Holmes did and what medical doctors do, and what we all do in our everyday lives. We apply general knowledge to specific cases to guide us in making choices and taking actions.

Technology and the applied sciences are sciences of method and therefore are largely deductive, deriving their basic principles from the more fundamental sciences on which they rest, for example, engineering from physics and chemistry, medicine from biology, and economics from psychology with several business disciplines drawing their basic principles from both psychology and economics.

This identification of deduction as application dispenses with the detached-from-reality deduction for the sake of deduction that has dominated the academic world since the Middle Ages. Deduction as application demonstrates how much deduction we practice in our everyday lives.

We all induce and deduce—some of us better (more accurately) and at greater length (in intensive study) than others. What Ayn Rand’s identifications mean is that induction and deduction are not a monopoly of scientists, philosophers, or academics in general.

Where then does measurement fit in the sciences? Conceptualization is universalization, which means its essence is measurement omission, which means the essence of theoretical science is measurement omission. This means that measurement is an aid to theoretical science, not its essence.

Measurement is crucial in the applied physical sciences when, for example, we want to send astronauts to the moon and back. Measurement in the biological and human sciences, however, is not quantitatively exact in the sense of constructing advanced mathematical equations to predict the behavior of animals or humans.

In the human sciences it is that annoying thing called free will—annoying to many human scientists, most of whom are materialists and determinists—that prevents the human scientists’ “elegant” equations from making any practical sense, or from being replicated in subsequent studies.**

The biological and human sciences are exact and valid, if the conceptualizations made by the scientists working in those fields have correctly identified the aspect of reality they are studying. The identifications are not equations, but they are quantitative. For example, psychological depression can be severe or mild.

“Measurement omission” does not mean that conceptualization ignores measurements. One individual case is quantitatively distinct from the next one, as two balls can be two different sizes and can be made of different materials.

Precise measurement is what technology and applied science, especially in the physical sciences, must critically pay attention to. Measurement in the applied biological and human sciences does not have to be so precise—because it cannot be.

“Truth,” to quote another succinct identification of Ayn Rand (Objectivist Epistemology, p. 48), “is the product of the recognition (i.e., the identification) of the facts of reality.” Truth, for Rand, is not a correspondence theory, but one that identifies facts. It is a recognition or identification theory.

And what is our guide to truth? Logic, of course, as “the art of non-contradictory identification” (Objectivist Epistemology, p. 36), not the mathematical or symbolic stuff that is taught in universities today or the medieval rationalism that permeates the older logic textbooks.

Induction and deduction are what we all use every day in our practical lives.

Induction and deduction, respectively, are conceptualization and application. Measurement is an important component of the two, but it is not their essence.


* See John P. McCaskey, “Induction in the Socratic Tradition,” in Shifting the Paradigm: Alternative Perspectives on Induction, ed. Louis F. Groarke & Paolo C. Biondi (Berlin: De Gruyter, 2014), 161–192, on his efforts to revive Socratic induction, a tradition promoted and debated both before and after Francis Bacon, but eventually overtaken by the nineteenth-century positivistic, Millian hypothetico-deductive method, a form of rationalistic, propositional inference. Socratic induction—generalization from particular things or concretes to universal abstract ideas—is consistent with Ayn Rand’s epistemology as inductive concept formation through measurement omission.

** “Man is that which fits economic equations,” as Ayn Rand (Capitalism: The Unknown Ideal, p. 7) so simply and aptly caricatured the very rationalistic, pseudo-deductive doctrine of pure and perfect competition in economics.